The present invention relates to a vehicle seat belt retractor, and more specifically to a seat belt retractor having a pawl which is moved into engagement with a ratchet wheel to block rotation of a seat belt storage spool in a seat belt withdrawal direction in response to withdrawal of a predetermined amount of the seat belt from the spool.
A known retractor having a pawl which is moved into engagement with a ratchet wheel to block rotation of a seat belt storage spool in a seat belt withdrawal direction in response to withdrawal of a predetermined amount of a seat belt from the spool is disclosed in U.S. Pat. No. 4,726,539. The retractor disclosed in this patent has a ring gear which is rotated during withdrawal of the seat belt. A pair of tabs are formed on the outside of the ring gear. Upon extension of a predetermined amount of the seat belt, one of the tabs engages an arm on a mode switching lever to pivot the switching lever. Pivotal movement of the switching lever actuates an overcenter spring to move a pawl into engagement with a ratchet wheel to block rotation of the spool in a seat belt withdrawal direction. Upon retraction of almost the entire length of the seat belt back onto the spool, a second arm on the switching lever is engaged by the other tab to pivot the switching lever. The overcenter spring is then actuated by the switching lever to move the pawl out of engagement with the ratchet wheel.